The present invention generally relates to mobile telephone units, and more particularly to a mobile telephone unit which enables connection of a portable mobile telephone and an automobile telephone.
The services of portable mobile telephones and automobile telephones are expanding, and the number of subscribers are increasing with this expansion. The portable mobile telephone is convenient to carry around because it is light. However, the portable mobile telephone uses an antenna with a relatively small gain and a transmission output of the portable mobile telephone is relatively small, thereby restricting the environment in which the portable mobile telephone can make a call. On the other hand, the automobile telephone can use an antenna with a relatively large gain, but the automobile telephone is heavy and is unsuited to carry around. Accordingly, there are demands to provide the advantageous features of both the portable mobile telephone and the automobile telephone into a single mobile telephone.
FIG.1 is a system block diagram for explaining an example of a conventional automobile telephone system and portable mobile telephone system. In FIG. 1, at least one of the communications company, the connecting conditions and the radio frequencies differs between two mobile communication networks 50 and 60.
The communication network 50 includes a mobile communication switching center 51 which is coupled to a public network 57, and a plurality of base stations 52-1 through 52-n which are coupled to the switching center 51 and respectively have antennas 53-1 through 53-n. In this case, portable mobile telephones 54 and 55 and an automobile telephone 56 are located in the area of the communication network 50.
On the other hand, the communication network 60 includes a mobile communication switching center 61 which is coupled to the public network 57, and a plurality of base stations 62-1 through 62-m which are coupled to the switching center 61 and respectively have antennas 63-1 through 63-m. In this case, portable telephones 64 and 65 and an automobile telephone 66 are located in the area of the communication network 60.
Telephone sets 58 and 59 of general subscribers are also coupled to the public network 57.
The portable mobile telephones 54 and 55 and the automobile telephone 56 make transmission and reception between the base stations 52-1 through 52-n. Similarly, the portable mobile telephones 64 and 65 and the automobile telephone 66 make transmission and reception between the base stations 62-1 through 62-m. FIG. 1 shows a case where the user of the portable telephone 55 rides in an automobile and uses the antenna or the like of the automobile telephone 56, and the user of the portable telephone 65 rides in an automobile and uses the antenna or the like of the automobile telephone 66.
When one of the portable telephones 54, 55, 64 and 65 and the automobile telephones 56 and 66 makes a call out, the subscriber's number of the caller is transmitted via the control channel together with the subscriber's number of the called end which is dialed. On the other hand, the call out from the base station is also detected by identifying the subscriber's number which is transmitted via the control channel.
For example, when a call out is made from the portable telephone 54 by dialing the subscriber's number of the general subscriber telephone 58, a call signal is transmitted to the general subscriber telephone 54 via the base station 52-1, the switching center 51 and a switching center of the public network 57. When the called subscriber answers to the call, a speech channel is specified by the switching center 51 or the base station 52-1, and the portable telephone 54 can make the call via this specified speech channel. In this case, if the connecting conditions, the radio frequencies and the like differ between the communication networks 50 and 60, the portable telephone 54 may not be able to connect to one of the base stations 62-1 through 62-m of the communication network 60.
In the automobile telephone system, an automobile telephone which is removable from the automobile when getting off the automobile has been proposed. According to this proposal, the automobile telephone can be used as a portable telephone by connecting a battery thereto. On the other hand, in the portable mobile telephone system, various technical improvements have been made to reduce the size, weight and power consumption of the portable telephone. As a result, a pocket-sized portable telephone has been developed.
In addition, the automobile telephones 56 and 66 use the battery of the automobile as the power unit, that is, a battery which has a relatively large capacity. The automobile telephones 56 and 66 use an antenna which has a relatively large gain and is designed for use on an automobile, so as to make the transmission and reception with one of the base stations 52-1 through 52-n and 62-1 through 62-m. Hence, the radio frequency used by the automobile telephones 56 and 66 is in the 800 MHz band, and the transmission output is approximately 5 W.
On the other hand, the portable telephones 55 and 65 use a compact secondary or primary battery as the power unit. The portable telephones 55 and 65 use an antenna which has a relatively small gain, such as an inverted F-type antenna and a whip antenna, so as to make the transmission and reception with one of the base stations 52-1 through 52-n and 62-1 through 62-m. Hence, the transmission output of the portable telephones 54 and 64 is approximately 1 W or less.
The portable telephone of the type described above may be carried when riding the automobile, and an adapter for connecting the portable telephone to the automobile telephone has been proposed. Such a connection is shown in FIG. 1 as a connection of the portable telephone 55 and the automobile telephone 56 and a connection of the portable telephone 65 and the automobile telephone 66. The proposed adapter connects the portable telephone to the automobile antenna which has the larger gain than that of the portable telephone, and also connects the portable telephone to the battery of the automobile having the larger capacity than that of the portable telephone. There has also been a proposal to connect the portable telephone to the automobile telephone via the adapter such as a cable so that a radio transmitter/receiver part of the automobile telephone can be utilized by the portable telephone.
Furthermore, there are many communications companies providing the portable telephone services. As a result the connecting conditions between the base station and the portable telephone, the radio frequencies and the like differ among the different communications companies. Thus, if a subscriber subscribes to one communications company, this subscriber can connect and communicate via the base station of this one communications company but cannot connect to the base stations of other communications companies. In addition, even in the case of the same communications company, the radio frequency band may be insufficient and different radio frequency bands may be used depending on the service area. Moreover, the communication system may be different among the communications companies, that is, one communications company may employ an analog system and another communications company may employ a digital system.
The size of the portable telephone is still decreasing with the technological improvements, and portable telephones of various shapes are being put on the market. For this reason, when the user carries the portable telephone when riding the automobile, the adapter for enabling the use of the automobile antenna, the radio transmitter/receiver part or the like of the automobile telephone may not be connectable to the portable telephone due to different specifications of the adapter and the portable telephone.
On the other hand, if the communications company providing the portable mobile telephone service and the communications company providing the automobile telephone service differ, there is a problem in that the portable telephone cannot use the radio transmitter/receiver part of the automobile telephone. In addition, even if the same communications company provides the portable mobile telephone service and the automobile telephone service, the portable telephone cannot use the radio transmitter/receiver part of the automobile telephone if the radio frequency bands used by the portable telephone and the automobile telephone differ.
In addition, if two or more people carry their portable telephones when riding the same automobile, the proposed adapter can only connect one of the portable telephones to the automobile telephone. The connection of the other portable telephones to the automobile telephone must wait until the call using the connected portable telephone is finished. After the call is finished, the user must perform the troublesome operation of disconnecting the connected portable telephone from the adapter and then connecting another portable telephone to the adapter. Therefore, there was a problem in that a satisfactory service cannot be provided if two or more people carry their portable telephones when riding in the same automobile or a bus mounted with the automobile telephone.
On the other hand, the automobile telephone which has a man-machine interface fixed to the automobile and the portable telephone which has a built-in man-machine interface and communication controller may use approximately the same radio frequency bands and line structures. In this case, the portable telephone can be connected to the automobile telephone to use the transmitter/receiver part and the antenna of the automobile telephone, so that a satisfactory call can be made even in a region on the periphery of the service area of the portable telephone. But there are demands to use the portable telephone by itself when away from the automobile and to use the portable telephone as an automobile telephone when within the automobile. For this reason, it is necessary to develop a standardized operating method and functions between the portable telephone and the automobile telephone.
In addition, the portable telephone is often provided with a function of storing various data such as telephone numbers and names. In such a case, it must be made possible to read and write the data regardless of whether the portable telephone is used by itself or connected to the automobile telephone and used within the automobile.
Furthermore, the automobile telephone system and the portable telephone system are provided by a plurality of communications companies that compete in the service and price, so that services employing different systems are receivable in the same region. For this reason, the effective system depends on the region in which the service is received, the region of the destination, the time for which the service is received and the like. Accordingly, if the portable telephone and the automobile telephone which are connected subscribe to different systems, it becomes necessary to selectively employ one of the two systems when making the call. Moreover, even if the service areas of the two systems differ, it must be possible to select the system which is providing the service in the region in which the portable telephone or automobile telephone is to be used.
FIG. 2 shows an example of a conventional mobile telephone unit. In FIG. 2, a portable telephone 100 includes a man-machine interface and a communication controller. The man-machine interface includes a microphone 111, a speaker 112, a display 113, a keyboard 114, and a central processing unit (CPU) 115 which controls the display 113 and the keyboard 114. The communication controller includes a CPU 101, a read only memory (ROM) 102 which prestores programs for executing software operations of the CPU 101, a random access memory (RAM) 103 for writing and reading data which are used for the control, and a programmable ROM 104 such as an electrically erasable programmable ROM (EEPROM) which prestores non-volatile information such as dialing numbers and identification (ID) information.
A switch 116 is provided between the man-machine interface and the communication controller of the portable telephone 100. The man-machine interface and the communication controller are connected when the switch 116 is connected to a terminal A, and. information can be exchanged in this case. The data from the CPU 101 and an audio signal from the microphone 111 are modulated by being passed through a baseband circuit 105 and a transmitter/receiver 106, and are transmitted to a base station (not shown) via an antenna 107. On the other hand, a radio signal from the base station is received by the transmitter/receiver 106 via the antenna 107 and is demodulated by being passed through the baseband circuit 105. Hence, the received audio signal is supplied to the speaker 112 via the switch 116, and the received data is supplied to the CPU 101.
On the other hand, an automobile telephone 200 includes a communication controller, a transmitter/receiver 206 and an antenna 207 which are fixedly provided on an automobile (not shown). The communication controller includes a CPU 210, a ROM 202 and a RAM 203. A handset 220 is connected to the communication controller via a signal interface. The handset 220 includes a microphone 211, a speaker 212, a display 213, a keyboard 214 and a CPU 215, similarly to the man-machine interface of the portable telephone 100. The microphone 211 is used to input the voice which is to be transmitted, and the speaker 212 is used to output the received voice. The display 213 displays the input from the keyboard 214, information related to the received data and the like.
According to this mobile telephone unit shown in FIG. 2, the CPU 201 and the baseband circuit 205 within the automobile telephone 200 and the CPU 101 and the baseband circuit 105 within the portable telephone 100 can be switched and connected to the man-machine interface (111-115) of the portable telephone 100 via the switch 116. Hence, when connecting the portable telephone 100 and the automobile telephone 200, the switch 116 is connected to a terminal B, so that the man-machine interface (111-115) of the portable telephone 100 is connected to the automobile telephone 200.
The control functions of the CPU 101 within the portable telephone 100 include a man-machine interface task (MMI TASK) 301 and a communication task 302 as shown in FIG. 3. The CPU 115 includes a display-keyboard control function 304. The exchange of information between the control functions of the CPU 100 and the display-keyboard control function 304 of the CPU 115 is prescribed as an interface 303. On the other hand, the control functions of the CPU 201 within the automobile telephone 200 includes a man-machine interface task 401 and a communication task 402 as shown in FIG. 3. In addition, the CPU 215 of the handset 220 includes a display-keyboard control function 404.
When connecting the portable telephone 100 and the automobile telephone 200, the switch 116 is connected to the terminal B. Hence, the exchange of information between the display-keyboard control function 304 of the CPU 115 within the portable telephone 100 and the man-machine interface task 401 within the automobile telephone 200 is made via an interface 403 as shown in FIG. 3. In other words, the portable telephone 100 is used in place of the handset 220, and the man-machine interface task 401 and the communication task 402 are carried out by the automobile telephone 200.
FIG. 4 shows another example of a conventional mobile telephone unit. In FIG. 4, those parts which are the same as those corresponding parts in FIG. 2 are designated by the same reference numerals, and a description thereof will be omitted.
In FIG. 4, the transmitter/receiver 106 of a portable telephone 500 includes a modulator 501, a transmitting amplifier 502, a transmitter/receiver duplexer 503, a receiving amplifier 504 and a demodulator 505. A dependent contact of the transmitter/receiver duplexer 503 is connected to a movable contact of a switch 506. A terminal A of the switch 506 is connected to the antenna 107, and a terminal B of this switch 506 is connected to a radio frequency (RF) interface 510.
On the other hand, an automobile telephone 600 at least includes a transmitter/receiver duplexer 601, a transmitting amplifier 602, a transmitter/receiver duplexer 603, an antenna 604, and a receiving amplifier 605. A dependent contact of the transmitter/receiver duplexer 601 is connected to the RF interface 510.
When the portable telephone 500 and the automobile telephone 600 are connected and used, the switch 506 is connected to the terminal B, and the transmitter/receiver duplexers 503 and 601 are connected via the RF interface 510 and the switch 506. Hence, at the time of the transmission, the data and audio signal from the baseband circuit 105 of the portable telephone 500 are modulated by the modulator 501 and amplified by the transmitting amplifier 502. The amplified data and audio signal are thereafter passed through the transmitter/receiver duplexer 503, the switch 506, the RF interface 510, the transmitter/receiver duplexer 601, the transmitting amplifier 602 and the transmitter/receiver duplexer 603, and are transmitted by radio from the antenna 604 of the automobile telephone 600 to the base station (not shown).
On the other hand, the signal received from the base station is received by the transmitter/receiver duplexer 603 via the antenna 604 of the automobile telephone 600. The received signal is amplified by the receiving amplifier 605, and is input to the portable telephone 500 via the transmitter/receiver duplexer 601 and the RF interface 510. This received signal is demodulated via the switch 506, the transmitter/receiver duplexer 503, the receiving amplifier 504 and the demodulator 505, and is then supplied to the baseband circuit 105. Hence, the received audio signal is supplied to the speaker 112, and the received data is supplied to the CPU 115 via the CPU 101.
Accordingly, according to this conventional mobile telephone unit shown in FIG. 4, when using the portable telephone 500 and the automobile telephone 600 in the connected state, the portable telephone 500 includes the man-machine interface task 301 and the communication function 302 of the CPU 101, and the display-keyboard control function 304 of the CPU 115, as shown in FIG. 5. On the other hand, the automobile telephone 600 is used as a booster which only has the function of amplifying the transmitting signal and the received signal, and the high-frequency signals are exchanged via the RF interface 510.
Therefore, according to the conventional mobile telephone unit shown in FIG. 2, even if the portable telephone 100 and the automobile telephone 200 are connected, the automobile telephone 200 must be provided with the man-machine interface task 401 which matches the man-machine interface task 301 of the portable telephone 100 which has various man-machine interface functions depending on each user, in order to standardize the operating method and functions between the case where the portable telephone 100 is used by itself and the case where the portable telephone 100 is connected to the automobile telephone 200 and used.
In addition, although the database such as the names and telephone numbers are provided within the portable telephone 100, the man-machine interface task 401 with respect to the key input is carried out in the automobile telephone 200. For this reason, the data transfer must be made from the automobile telephone 200 to the portable telephone 100 when writing data and the data transfer must be made from the portable telephone 100 to the automobile telephone 200 when reading data, thereby slowing down the response speed of the mobile telephone unit when making access to the database.
On the other hand, according to the conventional mobile telephone unit shown in FIG. 4, the call can only be made with the system to which the portable telephone 500 is subscribed, because the modem methods and the communication control methods differ among the systems. In order to enable the call to both the subscribed system of the portable telephone 500 and the subscribed system of the automobile telephone 600, the communication controller, the modulator and the demodulator must be designed to conform to the two different systems. As a result, even if a part of the circuitry is used in common between the two systems, it is still necessary to provide two independent circuit systems for a majority of parts of the communication controller, the modulator and the demodulator. In other words, the circuit construction becomes complex, and the cost of the unit becomes high. Furthermore, the software of the communication control function must be provided independently for the two systems.